CN104965010B - A kind of low temperature condenser type void fraction measuring device - Google Patents
A kind of low temperature condenser type void fraction measuring device Download PDFInfo
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- CN104965010B CN104965010B CN201510365937.3A CN201510365937A CN104965010B CN 104965010 B CN104965010 B CN 104965010B CN 201510365937 A CN201510365937 A CN 201510365937A CN 104965010 B CN104965010 B CN 104965010B
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- 239000011800 void material Substances 0.000 title claims abstract description 18
- 238000006243 chemical reaction Methods 0.000 claims abstract description 26
- 238000002474 experimental method Methods 0.000 claims abstract description 20
- 238000005259 measurement Methods 0.000 claims abstract description 19
- 230000005514 two-phase flow Effects 0.000 claims abstract description 16
- 238000012360 testing method Methods 0.000 claims abstract description 9
- 238000009413 insulation Methods 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 238000003466 welding Methods 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 230000005611 electricity Effects 0.000 claims description 4
- 239000003990 capacitor Substances 0.000 claims description 3
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- 230000002093 peripheral effect Effects 0.000 claims description 2
- 239000007788 liquid Substances 0.000 abstract description 11
- 238000000034 method Methods 0.000 abstract description 7
- 239000012530 fluid Substances 0.000 abstract description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- 229910052757 nitrogen Inorganic materials 0.000 description 9
- 239000012071 phase Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 102100034744 Cell division cycle 7-related protein kinase Human genes 0.000 description 1
- 101000945740 Homo sapiens Cell division cycle 7-related protein kinase Proteins 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
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- 230000005684 electric field Effects 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000002631 hypothermal effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000011368 organic material Substances 0.000 description 1
- 239000011505 plaster Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011555 saturated liquid Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The invention discloses a kind of measurement by capacitance low temperature two-phase-flow void fraction devices, including：Test pipeline, curved surface electrode, electro-magnetic screen layer, vacuum sleeve and data collecting system.Experiment pipeline is non-metallic insulation cry-fluid line, including upper and lower pipe interface.Data collecting system includes conversion circuit (CDC), I2C buses and computer；Electro-magnetic screen layer provides electromagnetic shielding for curved surface electrode.The principle that this method change using cryogen gas-liquid difference in dielectric constant and total dielectric constant with void fraction measures low temperature two-phase-flow void fraction indirectly, will not stream field generate and interfere, while have it is easy to operate, it is at low cost, respond the advantages that fast.
Description
Technical field
The present invention relates to cryogenic refrigeration field of engineering technology more particularly to a kind of low temperature condenser type void fraction measuring devices.
Background technology
Cryogenic two-phase flows are dynamic to be widely present in the fields such as the energy, space division, aerospace, and void fraction is as two phase flow
Important parameter in dynamic, it is closely related with manifold, local gas-liquid speed；Measurement and monitoring for void fraction, to two phase flow system
The normal operation of system and process control important.
Based on the method for void fraction in dielectric constant measurement two-phase flow, have response fast, at low cost, stream field is noiseless
Characteristic, be widely used in the real-time measurement of two-phase flow, such as oil-water-gas phase content measurement, refrigerant flow regime prison
Survey etc..Its measuring principle is that the electrode being arranged on runner both sides forms a capacitor, and capacitance is the dielectric constant of two-phase
With the function of phase content, phase content is calculated by measuring capacitance.The relative dielectric constant of most of gas is all very close
In 1, and compared to room temperature fluid water, refrigerant etc., the dielectric constant of cryogen wants smaller, such as table with corresponding gas difference
1。
Simultaneously as low temperature environment can make the dielectric constant of organic material change, measurement process can also be caused
It influences.Therefore, only Russian nuclear engineering research institute surveys the two-phase flow under low temperature environment using capacitance method at present
Amount, but its selection radio frequency method measurement capacitance speed is slower, it is difficult to meet measurement fluctuation characteristic.
Also document report can be used under profound hypothermia environment applying the measuring device of similar approach, Chinese patent CN
102759492 disclose it is a kind of using Method of Dielectric Coefficient measure cryogen density device, but the invention lay particular emphasis on measure it is quiet
The only low temperature two-phase mixture density under stable state cannot meet the cryogen measured under flow regime.Application number
A kind of gas-liquid two-phase flow containing rate real-time measurement of capacitance system and its measurement method announced for 201410146048.3, it is required that
Liquid phase dielectric constant is much larger than gas phase dielectric constant, is not suitable for the small cryogen of liquid phase dielectric constant difference.The U.S. is special
Sharp US5291791 discloses a kind of multi-electrode device measuring multinomial flowing, and main contents are flat by changing electric field measurement
Equal void fraction is not directed to specific manifold, and is not particularly illustrated to low temperature environment, the laminar flow not being suitable under low temperature.
Invention content
The present invention provides the accurate low temperature condenser type void fraction of one kind simple in structure, convenient test, test result and measures dress
It sets, which can relatively accurately measure the phase content of two phase flow in cryogenic piping, and then convenient for operating mode in monitoring pipe.
Technical scheme is as follows：
A kind of measurement by capacitance low temperature two-phase-flow void fraction device includes experiment pipeline, curved surface electrode, electro-magnetic screen layer, true
Empty set layer and data collecting system, the curved surface electrode and electro-magnetic screen layer patch and in experiment pipeline tube wall on, jointly extremely
In vacuum jacket, the data collecting system is made of capacitance digital conversion circuit, I2C buses and computer, electricity therein
Hold digital conversion circuit and the pole plate of experimental channel both sides is collectively disposed in vacuum layer, digital signal passes through vacuum data wire terminal
After be connected to I2C buses, communicated with computer.
The experimental channel, is low temperature resistant thinwalled insulation pipeline, and experimental channel is provided at both ends with inlet and outlet connectors, integrally puts
In vacuum jacket, there is vacuum data wire terminal on vacuum jacket.
The curved surface electrode is two panels sheet metal identical with experiment pipeline curvature, is close to test pipeline outside wall surface both sides
And be arranged symmetrically, welding lead on the outside of curved surface electrode, it is connected to capacitance digital conversion circuit, insulation is used simultaneously on the outside of curved surface electrode
Adhesive plaster wraps up.
The electro-magnetic screen layer, the long sheet metal of curved surface electrode is more than for width, and curved surface electrode is completely covered, inside
To be surrounded by the two panels curved surface electrode of insulating tape, separated by insulating tape therebetween, electro-magnetic screen layer welding lead is connected to
It is grounded in capacitance digital conversion circuit.
The capacitance digital conversion circuit, is made of capacitance number conversion chip and peripheral circuit, completes capacitance data and adopts
Collection and analog quantity to digital quantity conversion work, it is desirable that effective resolution reaches 4aF, at the same want renewal rate reach 20Hz with
On, to meet the measurement request of real-time.
The vacuum jacket, internal diameter are more than experiment pipeline, have vacuum data wire terminal.
The present invention is a kind of low temperature condenser type void fraction measuring device, is designed using non-intrusion type, simple in structure, test side
Just, original flow field is not influenced；Measuring speed is fast simultaneously, can there is real-time dynamic response with stream field.
Description of the drawings
Fig. 1 is low temperature condenser type void fraction measuring device cross-sectional view of the structure of the present invention；
Fig. 2 is low temperature condenser type void fraction measuring device structural schematic diagram of the present invention；
Fig. 3 is multiple steady flow capacitance and changes in flow rate.
Fig. 4 is that capacitance is verified with liquid level variation.
In figure：1, pipeline is tested, 2, curved surface electrode, 3, electro-magnetic screen layer, 4, vacuum jacket, 5, insulating tape, 6, experiment
Pipe interface, 7, capacitive digital converter, 8 vacuum data interfaces.
Specific implementation mode
The invention will be further described below in conjunction with the accompanying drawings, and embodiments of the present invention are not limited thereto.
As illustrated in fig. 1 and 2, a kind of measurement by capacitance low temperature two-phase-flow void fraction device includes experiment pipeline 1, curved surface electrode
2, electro-magnetic screen layer 3, vacuum jacket 4 and data collecting system, the curved surface electrode 2 and electro-magnetic screen layer 3 paste and in experiments
On the tube wall of pipeline 1, jointly as in vacuum jacket 4, the data collecting system is by capacitance digital conversion circuit 7, I2C buses
It is formed with computer, capacitance digital conversion circuit therein and the pole plate of 1 both sides of experimental channel are collectively disposed in vacuum layer 4, number
Word signal is connected to I2C buses after vacuum data wire terminal 8, is communicated with computer.
In one embodiment of the invention, the experimental channel 1 is low temperature resistant thinwalled insulation pipeline, experimental channel 1
Inlet and outlet connectors 6 are provided at both ends with, are integrally placed on 4 in vacuum jacket, there is vacuum data wire terminal 8 on vacuum jacket.
In one embodiment of the invention, the curved surface electrode 2 is two panels metal identical with experiment pipeline curvature
Piece is close to test 1 outside wall surface both sides of pipeline and is arranged symmetrically, welding lead on the outside of curved surface electrode, is connected to the conversion of capacitance number
Circuit 7,2 outside of curved surface electrode are wrapped up with insulating tape 5 simultaneously.
In one embodiment of the invention, the electro-magnetic screen layer 3 is more than the long sheet metal of curved surface electrode 2 for width,
And curved surface electrode 2 is completely covered, inside is the two panels curved surface electrode 2 for being surrounded by insulating tape 5, therebetween by insulating tape 5
It separates, 3 welding lead of electro-magnetic screen layer is connected in capacitance digital conversion circuit 7 and is grounded.
In one embodiment of the invention, the capacitance digital conversion circuit 7, by capacitance number conversion chip and periphery
Circuit forms, and completes the conversion work of capacitance data acquisition and analog quantity to digital quantity, it is desirable that effective resolution reaches 4aF, together
When want renewal rate to reach 20Hz or more, to meet the measurement request of real-time.
In one embodiment of the invention, the vacuum jacket 4, internal diameter are more than experiment pipeline, have vacuum data line
Connector 8.
In one embodiment of the invention, experimental bench is mainly by liquid nitrogen feed system, Heat Insulation Experiment pipe and measuring system
Three parts form.Saturation nitrogen with pressure extrudes saturated liquid nitrogen from Dewar, flow is controlled by changing pressure, by low temperature
Turbine flowmeter（Model：HOFFOR 1/4X1/4-.35-3.5, precision：±0.5%）, into experiment pipeline 1.Experimental channel is
Internal diameter 34mm, length 800mm silica glass material pipes, arranges capacitance sensor, while vacuum on the outside of use on experimental channel
Layer realizes the thermal insulation of experimental channel.
The highest snyed plate electrode structure of sensitivity is selected, and is tightly attached to the both sides of isolated pipe and symmetrically placed.Electricity
The copper thickness for holding electrode group is 0.5mm, and copper sheet width is 20mm, and cone of coverage α is 170 °.Include simultaneously for measuring electrode
The shielded layer of electromagnetic shielding is provided.
Data collecting system is mainly made of capacitance digital conversion circuit CDC7, I2C bus and computer, capacitance therein
Digital conversion circuit 7 and the pole plate of 1 both sides of experiment pipeline are collectively disposed in heat insulation layer, to reduce the transmission distance of analog signal to the greatest extent
From, while paying attention to carrying out shielded layer in surrounding them, reduce interference signal；Digital signal is connected to I2C after vacuum adapter
Bus is communicated with computer.Wherein capacitance digital conversion circuit 7 is mainly by the AD7746 chips of ADI companies and periphery electricity
Road forms, the main conversion work for completing capacitance data acquisition and analog quantity to digital quantity.AD7746 chips, effective resolution reach
To 21-bit, about 4aF, factory calibration accuracy 4fF；The renewal rate highest of the chip can reach 90Hz simultaneously, with
Meet the measurement request of real-time.
It first passes through a small amount of liquid nitrogen pipeline is pre-chilled, waits pipelines to be pre-chilled to liquid nitrogen temperature, then carry out test measurement.Experiment
Both sides curved surface electrode constitutes a capacitor in the process, changes the flow of liquid nitrogen, and two phase flow phase content is therewith in experimental channel
Variation, i.e., the electrolyte between curved surface electrode changes, and the variation of condenser capacitance value is measured by data collecting system, just
It can obtain phase changes of contents in low temperature two-phase-flow.
For experimental result as shown in figure 3, the line of dotted line is data on flows Q, the line of solid line is collected capacitance C.In reality
The flow of liquid nitrogen is varied multiple times during testing, it can be seen that capacitive sensor signal corresponding change occurs with flow meter signal
Change, in addition to the wave crest that bulk gas is formed by flowmeter when starting, the steady flow of a period of time, capacitance is often maintained also to exist
Fluctuation in certain range, it can be seen that the two signal height is related, and after closing liquid nitrogen valve, flow is zeroed rapidly, capacitance sensing
Device also reduces as far as possible.After being again turned on flowmeter, and occur, is to the last finished substantially to liquid nitrogen, interior appearance in runner
Bulk gas, capacitance sensor are gradually decrease to initial value.
Further to verify the accuracy that the present invention measures, continuous-stable flow regime all in Fig. 3 is read, is calculated
The average flow rate in this stage, application-level flow are assumed to calculate the height under corresponding flow.Capacitance increment is obtained with height to become
The experimental point of change is as shown in Figure 4.The theoretical curve being calculated based on finite element software is given in figure simultaneously, the two is being tested
Section coincide preferable.
Claims (2)
1. a kind of measurement by capacitance low temperature two-phase-flow void fraction device, which is characterized in that it includes experiment pipeline (1), curved surface electricity
Pole (2), electro-magnetic screen layer (3), vacuum jacket (4) and data collecting system, the curved surface electrode (2) and electro-magnetic screen layer
(3) it pastes and on the tube wall of experiment pipeline (1), jointly as in vacuum jacket (4), the data collecting system is by capacitance number
Conversion circuit (7), I2C buses and computer composition, capacitance digital conversion circuit (7) therein and experiment pipeline (1) both sides
Pole plate is collectively disposed in vacuum layer (4), and digital signal is connected to I2C buses after vacuum data wire terminal (8), with computer
It is communicated；
The experiment pipeline (1) is low temperature resistant thinwalled insulation pipeline, and experimental channel (1) is provided at both ends with inlet and outlet connectors (6),
Entirety is placed in vacuum jacket (4), has vacuum data wire terminal (8) on vacuum jacket (4)；
The curved surface electrode (2) is two panels sheet metal identical with experiment pipeline (1) curvature, is close to test pipeline (1) outside wall surface
Both sides are simultaneously arranged symmetrically, and welding lead on the outside of curved surface electrode (2) is connected to capacitance digital conversion circuit (7), curved surface electrode (2)
It is wrapped up simultaneously with insulating tape (5) in outside；
The copper thickness of curved surface electrode (2) group is 0.5mm, and copper sheet width is 20mm, and two pieces of capacitor plate cone of coverage α are 170 °；
The electro-magnetic screen layer (3), the long sheet metal of curved surface electrode (2) is more than for width, and curved surface electrode (2) is covered completely
Lid, inside is the two panels curved surface electrode (2) for being surrounded by insulating tape (5), is separated by insulating tape (5) therebetween, electromagnetic shielding
Layer (3) welding lead is connected to ground connection in capacitance digital conversion circuit (7)；
The capacitance digital conversion circuit (7), is made of capacitance number conversion chip and peripheral circuit, completes capacitance data acquisition
With the conversion work of analog quantity to digital quantity, it is desirable that effective resolution reaches 4aF, while renewal rate being wanted to reach 20Hz or more,
To meet the measurement request of real-time.
2. measurement by capacitance low temperature two-phase-flow void fraction device as described in claim 1, it is characterized in that the vacuum jacket
(4), internal diameter is more than experiment pipeline (1), has vacuum data wire terminal (8).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510365937.3A CN104965010B (en) | 2015-06-29 | 2015-06-29 | A kind of low temperature condenser type void fraction measuring device |
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| CN201510365937.3A CN104965010B (en) | 2015-06-29 | 2015-06-29 | A kind of low temperature condenser type void fraction measuring device |
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| CN104965010B true CN104965010B (en) | 2018-09-11 |
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| CN108845005A (en) * | 2018-06-22 | 2018-11-20 | 上海交通大学 | Suitable for heating the embedded cavity measuring sensor of plate channel two-phase flow |
| CN109275257B (en) * | 2018-07-24 | 2021-04-06 | 东莞中子科学中心 | Method for fixing an elongated material on the outer surface of a windable component and resulting object |
| CN110470704B (en) * | 2019-08-27 | 2020-09-29 | 浙江大学 | Capacitance tomography sensor applied to low-temperature fluid two-phase flow phase distribution measurement |
| JP7489490B2 (en) | 2020-12-09 | 2024-05-23 | 京セラ株式会社 | Air bubble rate sensor, flow meter using same, and cryogenic liquid transfer pipe |
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| GB8721858D0 (en) * | 1987-09-17 | 1987-10-21 | Schlumberger Ltd | Measurement apparatus |
| GB9109957D0 (en) * | 1991-05-08 | 1991-07-03 | Schlumberger Ltd | Capacitance flow meter |
| EP2856127B1 (en) * | 2012-05-31 | 2019-12-25 | Universiteit Gent | Methods and systems for characterizing void fractions of a substance flowing in a channel |
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